1. FIELD OF THE INVENTION
The present invention relates to an optical recording card and a method of producing the same.
In the recent years a number of cards in which various kinds of information are recorded are increasingly put in practical use as ID card, cash card or bank card.
2. DESCRIPTION OF THE PRIOR ART
This kind of card is required to record various kinds of informations such as data concerning individual person, data concerning a company from which the card is issued or the like data. In the earlier age such information was recorded using visual characters and symbols and in the later age they were recorded in response to electrical signals which were generated magnetically. However, due to rapid increase in number of cards the conventional card is not now in position to take adequate measures for preventing data from being falsified and moreover for the current tendency of increased volume of information.
In view of the current situation as mentioned above a card including an optical recording layer to which the latest optical technology is applied to record information has been developed in the recent years. This kind of card is called optical recording card.
To facilitate understanding of the present invention a conventional optical recording card which has been hitherto proposed will be described below as its basic structure with reference to FIG. 2. As is apparent from the drawing, the optical recording card 1 includes a card base 2, a protective layer 3 made of transparent plastic material and an optical recording layer 4 which is interposed between the card base 2 and the protective layer 3. Reading-out of information stored in the optical recording layer 4 is effected from the side of the protective layer 3. The optical recording layer 4 is provided with a light reflective layer which has an optical reflective surface. The optical reflective surface is formed with a number of data pits and reading-out of data is achieved by detecting presence and absence in dependency on the difference in optical reflectivity of each of the data pits while laser beaming is emitted toward the optical recording layer 4.
A conventional method which is hitherto employed for producing the optical recording mediums or optical recording cards including the same is typically practiced by way of the steps of forming a metallic reflective film over the whole surface of the base sheet in the form of a sheet having the same size as the card base by using a vacuum depositing process, placing optical information patterns on a part of the metallic reflective film serving as recording medium, removing the residual part of the same which is not used as recording medium and then adhesively securing to the card base the base sheet which includes the thus prepared optical recording medium.
In spite of the fact that the optical recording medium is usually provided on a part of the optical recording card, the method of producing the latter is practiced by way of the steps of preparing a base sheet in the form of a sheet having the same size as the card base, forming a metallic reflective film over the whole surface of the base sheet and removing an unnecessary part of the metallic reflective film which does not form optical information patterns, as mentioned above. This leads to a result of not only increased number of productions steps and elongated time required for production but also increased loss in material whereby the optical recording cards are produced at an expensive cost. Further since the optical recording medium is handled in the form of a sheet having the same size of the card base, it is difficult to improve productive efficiency.